Slide Fastener

ABSTRACT

A slide fastener configured in such a manner that fastener elements which are connected by connection sections are sewn in a stable attitude to the fastener tapes to increase the strength of attachment between the fastener tapes and the fastener elements. A slide fastener is provided with: a pair of fastener tapes ( 20 ); fastener element rows ( 30 ) having fastener elements ( 31 ) arranged in rows at constant intervals along opposing tape side edges ( 20   a ) of the pair of fastener tapes ( 20 ); and a slider ( 40 ) attached so that the slider ( 40 ) can slide along the fastener element rows ( 30 ) and can engage and disengage the fastener elements ( 31 ) from each other. The fastener elements ( 31 ) are connected by connection sections ( 22 ) to form the fastener element rows ( 30 ), and the fastener elements ( 31 ) are attached to the fastener tapes ( 20 ) by two or more sewing threads ( 38 ) to the surface of the fastener elements ( 31 ) so as to be disposed side by side in the widthwise direction of the fastener tapes ( 20 ).

TECHNICAL FIELD

The present invention relates to a slide fastener, and more particularly, to a slide fastener including a plurality of fastener elements which are engaged by a coupling portion.

BACKGROUND ART

A related-art slide fastener is known in the art, in which fastener element rows having a plurality of fastener elements connected by a support strip to be embedded are sewn along opposing tape-side edges of a pair of fastener tapes (e.g., see Patent Document 1).

PRIOR ART DOCUMENT Patent Document

-   Patent Document 1: Japanese Patent Application Publication No.     S56-089204A

SUMMARY OF INVENTION Problems to Be Solved by Invention

In the slide fastener disclosed in Patent Document 1, however, for example, when the fastener element rows are sewn to the fastener tapes using a sewing machine, the posture of the fastener elements is not stable, so that it is difficult to sew the fastener elements to the fastener tapes in a stable posture. If the fastener elements are sewn in the unstable posture, attachment strength of the fastener elements to the fastener tapes is not sufficient. As a result, the fastener elements move with respect to the fastener tapes, or the fastener elements are not appropriately engaged with each other.

The present invention has been made in view of the above-described problem, and an object of the present invention is to provide a slide fastener capable of increasing attachment strength of fastener elements to fastener tapes by sewing a plurality of fastener elements which are connected by a coupling portion to the fastener tapes in a stable posture.

Means for Solving Problems

The above object of the present invention can be achieved by the following configuration.

(1) A slide fastener including: a pair of fastener tapes; fastener element rows including a plurality of fastener elements arranged at a regular interval along opposing tape-side edges of the pair of fastener tapes; and a slider slidably attached along the fastener element rows to engage and disengage the fastener elements, wherein each of the fastener elements includes a body portion attached to one of the fastener tapes, a neck portion extending outward from the body portion in a width direction of the fastener tapes, and constricted in a longitudinal direction of the fastener tapes, and an engaging head portion extending from a tip end portion of the neck portion and swelling up in the longitudinal direction of the fastener tapes relative to the neck portion, and wherein the fastener elements are connected to each other by at least one coupling portion to configure one of the fastener element rows, and are attached to one of the fastener tapes by two or more sewing yarns which are arranged on a surface of each of the fastener elements in the width direction of the fastener tapes.

(2) The slide fastener according to (1), wherein each of the fastener elements has a first surface which is in contact with the one of the fastener tapes, and a second surface opposite to the first surface, wherein a side of the first surface has the body portion, the neck portion extending from the body portion, and the engaging head portion extending from the tip end portion of the neck portion, and wherein a side of the second surface has a head portion extending outward from the body portion toward in the width direction of the fastener tapes, and gradually decreasing in a dimension thereof in the longitudinal direction of the fastener tapes toward a tip end thereof.

(3) The slide fastener according to (1) or (2), wherein the surface of each of the fastener elements is formed with accommodation grooves for accommodating the sewing yarns.

(4) The slide fastener according to any one of (1) to (3), wherein the plurality of fastener elements are connected to each other by a pair of coupling portions to configure the one of the fastener element rows, and are attached to the one of the fastener tapes by two sewing yarns.

(5) The slide fastener according to (4), wherein the two sewing yarns are disposed between the pair of coupling portions.

(6) The slide fastener according to (1), wherein each of the fastener elements has a first surface which is in contact with the one of the fastener tapes, and a second surface opposite to the first surface, and wherein the first surface is formed with a curved portion which is curved concavely toward the second surface.

Advantageous Effects of Invention

According to the slide fastener of the present invention, the fastener elements are connected to each other by the coupling portion to configure the fastener element row, and are attached to the fastener tape by two or more sewing yarns which are arranged in the width direction of the fastener tapes on the surfaces of each of the fastener elements. Therefore, the fastener elements can be attached to the fastener tapes in a stable posture, thereby increasing the attachment strength of the fastener elements to the fastener tapes.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a front side view illustrating a slide fastener according to one embodiment of the present invention;

FIG. 2 is an enlarged perspective view illustrating a fastener element row which is not engaged;

FIG. 3 is a front side view of the fastener element row shown in FIG. 2;

FIG. 4 is a back side view of the fastener element row shown in FIG. 2;

FIG. 5 is a cross-sectional view taken along the line A-A in FIG. 1;

FIG. 6 is an main-part-enlarged front side view illustrating an engaging or disengaging state of fastener elements in a slider;

FIG. 7 is a cross-sectional view taken along the line B-B in FIG. 1;

FIG. 8 is a cross-sectional view illustrating a state in which the slide fastener in FIG. 7 is bent in a front and back direction;

FIG. 9 is an enlarged cross-sectional view illustrating a modification of the slide fastener of the first embodiment;

FIG. 10 is a cross-sectional view illustrating a slide fastener according to a second embodiment of the present invention;

FIG. 11 is a front side view of the fastener element row in FIG. 10;

FIG. 12 is a cross-sectional view illustrating a slide fastener according to a third embodiment of the present invention;

FIG. 13 is a front side view of the fastener element row in FIG. 12; and

FIG. 14 is a front side view illustrating a fastener element row to illustrate a slide fastener according to a third embodiment of the present invention.

EMBODIMENTS OF INVENTION

Embodiments of a slide fastener according to the present invention will now be described in detail with reference to the accompanying drawings. In the following description, as for fastener tapes, a front side refers to a near side with respect to the paper surface of FIG. 1 (i.e., an upper side of a slider, on which a pull tab is provided, as will be described later), a back side refers to a far side with respect to the paper surface of FIG. 1 (i.e., a lower side of the slider, on which the pull tab is not provided, as will be described later), a front side refers to an upper side with respect to the paper surface of FIG. 1 (i.e., a side of a direction in which the slider is moved to engage fastener element rows, as will be described later), a rear side refers to a lower side with respect to the paper surface of FIG. 1 (i.e., a side of a direction in which the slider is moved to disengage the fastener element rows, as will be described later), a left side refers to a left side with respect to the paper surface of FIG. 1, and a right side refers to a right side with respect to the paper surface of FIG. 1. As for the slider, an upper side refers to a near side with respect to the paper surface of FIG. 1, a lower side refers to a far side with respect to the paper surface of FIG. 1, a front side refers to an upper side with respect to the paper surface of FIG. 1, a rear side refers to a lower side with respect to the paper surface of FIG. 1, a left side refers to a left side with respect to the paper surface of FIG. 1, and a right side refers to a right side with respect to the paper surface of FIG. 1. Herein, a front and back direction refers to a direction perpendicular to a surface of the fastener tapes, and a left and right direction refers to a direction perpendicular to the front and back direction and parallel with the surface of the fastener tape. Further, a left and right direction of the fastener tape and the slider refers to a width direction. Also, the front and rear direction of the fastener tapes refers to a longitudinal direction.

Embodiment 1

First, the first embodiment of the slide fastener according to the present invention will now be described with reference to FIGS. 1 to 9.

A slide fastener 10 of this embodiment includes a pair of left and right fastener tapes 20 made by weave or knit, a pair of left and right fastener element rows 30 each attached to opposing tape-side edges 20 a of the pair of left and right fastener tapes 20, a slider 40 for engaging and disengaging the left and right fastener element rows 30, top end stops 11 made by injection molding to respectively cover fastener elements 31 at front end portions of the left and right fastener element rows 30, and a bottom end stop 12 made by injection molding to cover both fastener elements 31 at rear end portions of both fastener element rows 30, 30. As the slider 40 is moved in the front and back direction, the left and right fastener element rows 30 are engaged and disengaged with and from each other. In this instance, the bottom end stop 12 may be a separable end stop having an insert pin, a box pin, and a box body. In this instance, in FIGS. 1 and 2, sewing yarns 38 are not illustrated to show the respective components.

The pair of left and right element rows 30 include a plurality of fastener elements 31 independent of each other, which are arranged in one row along the longitudinal direction of the tape-side edges 20 a of the fastener tapes 20, and a pair of coupling portions having a circular shape in cross section, which are arranged parallel with each other in the width direction of the fastener tape 20 to connect the adjacent fastener elements 31. Further, the plurality of fastener elements 31 and the coupling portions are integrally molded by injection molding using synthetic resin, for example, polyamide, polyacetal, polypropylene, or polybutylene terephthalate. In this instance, the fastener elements 31 are not limited to the synthetic resin, but may be made of metal.

Since the plurality of fastener elements 31 are integrally connected to each other by the pair of coupling portions 22 disposed in parallel, a posture (positional relation) of each fastener element 31 is maintained stably. Accordingly, the fastener elements 31 can be sewn to the fastener tape 20 in the stable posture, thereby increasing attachment strength of the fastener elements 31 to the fastener tape 20. Further, it is possible to easily and reliably carry out the sewing work. The coupling portion 22 may be a member different from the fastener elements 31, for example, a string type member such as yarn. In this instance, the fastener elements 31 are injection-molded at regular intervals on two string type members which are continuous in a longitudinal direction of the fastener tape 20, and then the string type member is insert-molded in the fastener elements 31.

The fastener element 31 includes, as illustrated in FIGS. 2 to 5, a back-surface portion 32A which is a first surface being in contact with the fastener tape 20, and a front-surface portion 32B which is a second surface being opposite to the back-surface portion 32A and disposed on a front side.

The side of the back-surface portion 32A has, as illustrated in FIG. 4, a body portion 33 attached to the fastener tape 20, a neck portion 34 extending outward (in the right direction in the drawing, i.e., a direction toward the opposite fastener element row 30 from the state attached to the fastener tape 20) from the body portion 33 in a width direction of the fastener tape 20 (tape width direction), and constricted in the longitudinal direction of the fastener tape 20 (tape longitudinal direction), and an engaging head portion 35 extending outward from a tip end portion of the neck portion 34 in the width direction of the fastener tape 20, and swelling up in the longitudinal direction of the fastener tape 20 relative to the neck portion 34. Further, a dimension of the neck portion 34 in the tape longitudinal direction is smaller than that of the body portion 33 and the engaging head portion 35. A dimension of the engaging head portion 35 in the tape longitudinal direction is larger than that of the body portion 33.

The body portion 33 is a cube having a substantially rectangular shape which is elongated in the width direction of the fastener tape 20 in a plan view, and is respectively formed with the pair of coupling portions 22 from both sides of the fastener tape 20 in the longitudinal direction. The pair of coupling portions 22 connect the body portions 33 of the adjacent fastener elements 31, and has one coupling portion for coupling the portions of the respective body portions 33 at the side of the engaging head portions 35, and the other coupling portion which is spaced apart from the one coupling portion for coupling the portions of the body portions 33 at the side opposite to the engaging head portions 35. Further, an end face of the body portion 33 at the side opposite to the engaging head portion 35 is formed with a protruding curved surface 33 a of which a center portion in the longitudinal direction of the fastener tape 20 protrudes toward the side opposite to the engaging head portion 35. Further, a curved portion 33 b which is concavely curved in a direction toward the front-surface portion 32B is formed on a back surface of the body portion 33 (surface coming into contact with the fastener tape 20) between the pair of coupling portions 22 (see FIG. 5). When the left and right fastener element rows 30 are engaged, the engaging head portion 35 is engaged with the neck portion 34 of the adjacent fastener element 31. The body portion 33 at the side of the protruding curved surface 33 a is formed so as to gradually increase in a dimension thereof in the width direction of the fastener tape 20 toward the front-surface portion 32B from the back-surface portion 32A, as illustrated in FIG. 5, and gradually decrease in the dimension at a position beyond the coupling portion 22. The coupling portion 22 coupling the adjacent fastener elements 31 has a thickness thinner than that of the fastener elements 31 in the front and back direction of the fastener element 31, and extends in the longitudinal direction of the fastener tape 20 (direction perpendicular to the width direction of the fastener tape 20). The cross-sectional shape of the coupling portion 22 is not limited to the circle, and may be a rectangular shape or an oval shape.

The side of the front-surface portion 32B has a front-side head portion 36 having a substantially triangular shape in a plan view which extends outward from the body portion 33 in the width direction of the fastener tape 20, and gradually decreases in a dimension thereof in the longitudinal direction of the fastener tape 20 toward a tip end thereof. The front-side head portion 36 is formed on the front side of the engaging head portion 35 and the neck portion at the side of the back-surface portion 32A. That is, the neck portion 34 and the engaging head portion 35 are provided so as to extend from the side of the back-surface portion 32A of the body portion 33, and the front-side head portion 36 is provided so as to extend from the side of the front-surface portion 32B of the body portion 33.

Further, the front surface and the side surfaces of the body portion 33 between the pair of coupling portions 22 are formed with two concave accommodation grooves 37 for respectively accommodating two sewing yarns 38, which will be described later, and the accommodation grooves 37 are formed in parallel with the coupling portions 22 to be continuously on both the side surfaces and the front surface of the body portion 33.

The slider 40 includes, as illustrated in FIGS. 1, 5 and 6, an upper blade 41 and a lower blade 42 which are disposed in parallel while being spaced apart from each other in a up-down direction, a guide post 43 for connecting the upper blade 41 and the lower blade 42 at front ends thereof, flanges 44 formed along both left and right edges of the upper blade 41 and the lower blade 42, a pull tab attachment post 45 formed on an upper surface of the upper blade 41, and a pull tab 46 swingably attached to the pull tab attachment post 45. Accordingly, a front portion of the slider 40 is formed with left and right shoulder mouths 47 which are separated by the guide post 43, and a rear portion of the slider 40 is formed with a rear mouth 48. An approximately Y-shaped element guide passage 49 is formed between the upper blade 41 and the lower blade 42 to communicate the left and right shoulder mouths 47 and the rear mouth 48, and the element guide passage 49 forms a path through which the pair of left and right fastener element rows 30 are inserted. In this instance, the flanges 44 may be provided on only one of the upper blade 41 and the lower blade 42, and the pull tab attachment post 45 and the pull tab 46 may be provided on the lower blade 42 only.

In this embodiment, if the slider 40 is operated to move, the protruding curved surface 33 a of the fastener element 31 is in sliding contact with the flange 44, and thus a contact area between the flange 44 and the protruding curved surface 33 a is smaller than that of a flat surface. Accordingly, since the sliding resistance generated when the slider 40 is moved can be decreased, the slider 40 can be operated by small power.

As illustrated in FIG. 5, as each fastener element 31 is sewn along the tape-side edge 20 a at one surface side (e.g., front side) of the fastener tape 20 by two sewing yarns 38 which are arranged in the width direction of the fastener tape 20, the fastener element row 30 is attached to the fastener tape 20. After the two sewing yarns 38 straddle the front surfaces of the body portions 33 of the adjacent fastener elements 31 in the longitudinal direction of the fastener tape 20, the sewing yarns 38 are sewn to the fastener tape 20 between the fastener elements 31, so that the fastener elements 31 are sewn to the fastener tape 20. The two sewing yarns 38 has one sewing yarn 38 disposed at the side of the engaging head portion 35 of the body portion 33, and the other sewing yarn 38 spaced apart from the one sewing yarn 38 and disposed at the side of the engaging head portion 35 of the body portion 33. Further, the number of sewing yarns 38 may be three.

Since the two sewing yarns 38 are respectively accommodated in the accommodation grooves 37, the two sewing yarns 38 do not released from the fastener elements 31. Further, since the fastener tape 20 is sewn so as to be in close contact with the curved portion 33 b at the back surface of the body portion 33, the attachment strength of the fastener elements 31 to the fastener tape 20 is improved.

In the slide fastener 10 configured as described above, as illustrated in FIGS. 6 and 7, the engaging head portions 35 of the left and right fastener elements 31 are engaged with each other in a state where the upper surface of the engaging head portion 35 of one of the fastener elements 31 and the lower surface of the front-side head portion 36 of another of the fastener elements 31 abut against each other. As illustrated in FIG. 7, the neck portion 34 and the engaging head portion 35 are formed into a substantially trapezoidal shape in cross section which is tapered from the center thereof in the front and back direction toward the back side, and the front-side head portion 36 is formed into a substantially trapezoidal shape in cross section which is tapered from the center thereof in the front and back direction toward the front side. Accordingly, the left and right engaged fastener elements 31 are engaged with each other relatively in a state with a gap. For this reason, as illustrated in FIG. 8, even though the slide fastener 10 is bent toward the front direction, the fastener elements 31 are hardly in contact with each other, so that the slide fastener can be easily bent while maintaining the good engaging state. Further, even though the slide fastener is bent in the back direction opposite to FIG. 8, since the engaging head portion 35 is tapered toward the back side from the center thereof in the front and back direction, the slide fastener can be easily bent.

As described above, according to the slide fastener 1 of this embodiment, the fastener elements 31 are connected to each other by the pair of coupling portions 22 to configure the fastener element row 30, and are attached to the fastener tape 20 by the two sewing yarns 38 which are arranged in the width direction of the fastener tape 20 on the front surfaces of the fastener elements 31. Therefore, the fastener elements 31 can be attached to the fastener tape 20 in the stable posture, thereby increasing the attachment strength of the fastener elements 31 to the fastener tape 20.

According to the slide fastener 10 of this embodiment, since the body portion 33 is formed with the two accommodation grooves 37 for respectively accommodating two sewing yarns 38, the two sewing yarns 38 are not released from the fastener elements 31. Accordingly, the fastener elements 31 can be reliably attached to the fastener tape 20.

According to the slide fastener 10 of this embodiment, since the two sewing yarns 38 are disposed between the pair of coupling portions 22, it is possible to prevent the sewing yarns 38 from being in contact with an external member by the pair of coupling portions 22. Accordingly, the wearing of the sewing yarns 38 due to the contact can be prevented, thereby increasing the durability of the slide fastener 10.

According to the slide fastener 10 of this embodiment, since the back-surface portion 32A of the fastener element 31 is formed with the curved portion 33 b which is concavely curved toward the front-surface portion 32B, when the fastener elements 31 are sewn to the fastener tape 20, the fastener tape 20 is in close contact with the curved portion 33 b, thereby increasing the attachment strength of the fastener elements 31 to the fastener tape 20.

As a modification of this embodiment, the fastener element row 30 may be applied to a concealed slide fastener 50 illustrated in FIG. 9. The concealed slide fastener 50 includes a pair of left and right fastener tapes 51, the fastener element rows 30 each sewn along bent edges 51 b which are formed by bending the opposing tape-side edges 51 a of the pair of left and right fastener tapes 51 into substantially U-shapes, and a slider 60 for engaging and disengaging the left and right fastener element rows 30. As the left and right bent edges 51 b approach to, or preferably, in contact with each other when the fastener element rows 30 are engaged, the fastener element rows 30 are hardly seen from the front side.

The slider 60 includes a lower blade 61, a pair of left and right flanges 62 having an inverted L-shapes in cross section, the flanges having side wall portions 62 a erected along left and right side edges of the lower blade 61 and a pair of left and right upper plate portions 62 b extending from upper ends of the left and right side wall portions 62 a in a mutually approaching direction, a guide post (not illustrated) erected from the front end portion of the lower blade 61 toward the pair of left and right upper plate portions 62 b, and a pull tab (not illustrated) swingably attached to the guide post.

Embodiment 2

Next, a slide fastener according to the second embodiment of the present invention will now be described with reference to FIGS. 10 and 11. In this instance, the same reference numerals are applied to elements identical or equivalent to those in the first embodiment and the description thereof is omitted or simplified.

In this embodiment, as illustrated in FIGS. 10 and 11, the front surface of the body portion 33 of the fastener element 31 is formed with one wide accommodation groove 71 for accommodating the sewing yarns 38. Further, the coupling portions 22 at the side of the protruding curved surface 33 a of the body portion 33 are disposed at the substantially center portion of the accommodation groove 71 in the width direction. The fastener elements 31 are sewn to the fastener tape 20 by three sewing yarns 38. Two sewing yarns 38 pass between the pair of the coupling portions 22 and one sewing yarn 38 passes the outside of the coupling portion 22 at the side of the protruding curved surface 33 a in the width direction.

In addition, the front surface of the fastener tape 20 is formed with a waterproof layer 72 by adhering a film-like material made of thermoplastic synthetic resin (thermoplastic elastomer) with using an adhesive or applying molten resin thinly. Since the waterproof layer 72 is formed on the fastener tape 20, the fastener elements 31 are used so as to disposed at the back side to prevent penetration of rainwater or the like, thereby providing the slide fastener with a waterproof performance.

Other configurations and working effects thereof are identical to those of the first embodiment.

Embodiment 3

Next, a slide fastener according to the third embodiment of the present invention will now be described with reference to FIGS. 12 and 13. In this instance, the same reference numerals are applied to elements identical or equivalent to those in the first embodiment and the description thereof is omitted or simplified.

In this embodiment, as illustrated in FIGS. 12 and 13, the fastener elements 31 are connected to each other by one flat-shaped coupling portion 81. The coupling portion 81 is integrally formed with the fastener elements 31, as well as the coupling portion 22. Further, two sewing yarns 38 penetrate the coupling portion 81 to sew the fastener elements 31 to the fastener tape 20. It is preferable that, between the vicinity of the neck portion 34 of the fastener element 31 and the vicinity of the protruding curved surface 33 a, the coupling portion 81 is of a sufficient width so that at least one sewing yarn 38 penetrates (is sewn to) the coupling portion 81.

As described above, according to the slide fastener 10 of this embodiment, since the fastener elements 31 are connected to each other by the flat-shaped coupling portion 81, the posture of the fastener elements 31 can be further stabilized. Since the two sewing yarns 38 penetrate the flat-shaped coupling portion 81, the attachment strength of the fastener elements 31 to the fastener tape 20 can be further increased.

Other configurations and working effects thereof are identical to those of the first embodiment.

Embodiment 4

Next, a slide fastener according to the fourth embodiment of the present invention will now be described with reference to FIG. 14. In this instance, the same reference numerals are applied to elements identical or equivalent to those in the first embodiment and the description thereof is omitted or simplified.

In this embodiment, fastener elements 91 illustrated in FIG. 14 are used, instead of the fastener elements 31. The fastener element 91 is formed to have the same shape in the front and back sides, and, as well as the fastener element 31, includes a body portion 92 formed with two accommodation grooves 93, a neck portion 94 extending outward from the body portion 92 in a width direction of the fastener tape 20 (in the right direction in the drawing) and constricted in the longitudinal direction of the fastener tape 20, an engaging head portion 95 further extending outward from a tip end portion of the neck portion 94 in the width direction of the fastener tape 20 and swelling up in the longitudinal direction of the fastener tape 20 relative to the neck portion 94, a pair of shoulder portions 96 extending from side surfaces of the neck portion 94, and a shoulder portion accommodating groove 97 formed at a tip end portion of the engaging head portion 95 so as to be fitted with the shoulder portion 96 of the opposite fastener element 91. In this instance, the fastener elements 91 are sewn to the fastener tape 20 by the two sewing yarns 38, as well as the fastener elements 31.

Other configurations and working effects thereof are identical to those of the first embodiment.

The present invention is not limited to the above-described embodiment, and can be properly modified or revised without being deviated from the gist of the invention.

For example, in the above embodiment, the back-surface portion 32A of the fastener element 31 may be formed to have a flat surface, so that the curved portion 33 b is not formed.

DESCRIPTION OF REFERENCE NUMERALS

-   -   10: Slide Fastener     -   20: Fastener Tape     -   20 a: Tape-Side Edge     -   22: Coupling Portion     -   30: Fastener Element Row     -   31: Fastener Element     -   32A: Back-Surface Portion (First Surface)     -   32B: Front-Surface Portion (Second Surface)     -   33: Body Portion     -   33 b: Curved Portion     -   34: Neck Portion     -   35: Engaging Head Portion     -   36: Front-Side Head Portion (Head Portion)     -   37: Accommodation Groove     -   38: Sewing Yarn     -   40: Slider     -   71: Accommodation Groove     -   81: Coupling Portion     -   91: Fastener Element     -   92: Body Portion     -   93: Accommodation Groove     -   94: Neck Portion     -   95: Engaging Head Portion 

1. A slide fastener comprising: a pair of fastener tapes; fastener element rows including a plurality of fastener elements arranged at a regular interval along opposing tape-side edges of the pair of fastener tapes; and a slider slidably attached along the fastener element rows to engage and disengage the fastener elements, wherein each of the fastener elements includes a body portion attached to one of the fastener tapes, a neck portion extending outward from the body portion in a width direction of the fastener tapes and constricted in a longitudinal direction of the fastener tapes, and an engaging head portion extending from a tip end portion of the neck portion and swelling up in the longitudinal direction of the fastener tapes relative to the neck portion, and wherein the fastener elements are connected to each other by at least one coupling portion to configure one of the fastener element rows, and are attached to one of the fastener tapes by two or more sewing yarns which are arranged on a surface of each of the fastener elements in the width direction of the fastener tapes.
 2. The slide fastener according to claim 1, wherein each of the fastener elements has a first surface which is in contact with the one of the fastener tapes, and a second surface opposite to the first surface, wherein a side of the first surface has the body portion, the neck portion extending from the body portion, and the engaging head portion extending from the tip end portion of the neck portion, and wherein a side of the second surface has a head portion extending outward from the body portion in the width direction of the fastener tapes and gradually decreasing in a dimension thereof in the longitudinal direction of the fastener tapes toward a tip end thereof.
 3. The slide fastener according to claim 1, wherein the surface of each of the fastener elements is formed with accommodation grooves for accommodating the sewing yarns.
 4. The slide fastener according claim 1, wherein the plurality of fastener elements are connected to each other by a pair of coupling portions to configure the one of the fastener element rows, and are attached to the one of the fastener tapes by two sewing yarns.
 5. The slide fastener according to claim 4, wherein the two sewing yarns are disposed between the pair of coupling portions.
 6. The slide fastener according to claim 1, wherein each of the fastener elements has a first surface which is in contact with the one of the fastener tapes, and a second surface opposite to the first surface, and wherein the first surface is formed with a curved portion which is curved concavely toward the second surface. 